The present invention broadly relates to display devices. More particularly, the invention relates to erasable marker boards of the type classified in U.S. Class 434, subclass 417 or U.S. Class 528, subclass 207.
In many instances conventional chalkboards have given way to plastic-coated boards upon which felt tip markers can be used. The latter boards are easily erased. Other advantages of these marker boards include relatively low weight and reduced production costs. In a classroom application, large sections of plastic-coated board can easily be hung in place of a conventional chalkboard. However, many instances call for a smaller board which can be quickly and easily impermanently mounted upon a wall. Furthermore, such a board needs to be somewhat portable. Therefore, the need for a unitary lightweight structurally sound marker board is evident. To create such a board a manufacturer will be required to frame the plastic marking surface.
Many frame elements are present in the prior art. Hutten U.S. Pat. No. 4,623,169 discloses an apparatus for clamping. This device is intended to clamp a pad of papers to an upright support. Hutten also discloses in U.S. Pat. No. 4,629,275 a mounting strip for clamping similar flexible sheet materials. That clamp is largely composed of a plastic channel with a gripper tongue disposed along an interior surface.
Champagne in U.S. Pat. No. 4,230,052 granted Oct. 28, 1980, discloses a corner support system for shelves. The system has triangular shaped elements to reinforce a corner of the shelving system. U.S. Pat. No. 4,747,248 granted May 31, 1988, to Fahs discloses a method for corner construction. This method comprises elaborate cuts in frame members to form the corner of an aluminum window or door.
Design Pat. No. 286,434 discloses a plastic window frame corner which has a plurality of intermittent walls and ridges to accommodate the relatively complex structure of an insulated window frame. Schiavello U.S. Pat. No. 4,852,317 speaks to a demountable panel system. The primary operative component of this invention is a bracket of relatively complex structure which employs clip rail sections to trap and hold a plurality of panels in a spaced apart relationship. Bucci U.S. Pat. No. 4,987,709 discloses a frame construction system. This system uses corner reinforcement members that employ wedges between two channels adapted to receive a pane of glass. Warner U.S. Pat. No. 4,064,644 speaks to a frame construction and corner clip apparatus. The frame is constructed of extruded metallic material having an "F" shaped cross-section and a corner bracket that is "L" shaped to join the ends of the "F" shaped material. The bracket has channels adapted to receive the "F" shaped material.
U.S. Pat. No. 4,662,092 discloses a picture frame construction. This patent primarily discloses a corner bracket that is intended to create a curved transition from one piece of an "F" shaped extruded frame material to another. Field U.S. Pat. No. 4,898,285 discloses a merchandise rack covering system. This system is comprised of semi-circular tubing intended to be disposed over the square members of a merchandise rake and corner brackets to join the semi-circular tube sections. Machler discloses in U.S. Pat. No. 4,502,260 corner fasteners. These corner fasteners are intended for use on window screens and employ a resilient finger of a hemispherical shape extending from the corner to facilitate securement within a window frame. Nielsen U.S. Pat. No. 3,965,601 discloses an "L" shaped corner bracket for insertion into the mitered corners of a picture frame extrusion. Paskerian U.S. Pat. No. 3,965,600 discloses a picture frame hanger. This hanger is a "U" shaped plate which may be slide into the channels of a conventional picture frame.
Some prior art suggests the use of a frame to surround a board intended to convey information. Seely U.S. Pat. No. 4,519,152 discloses a theft proof poster display device. This device is intended to have a pivoting front frame and is similar to conventional movie poster display systems. Weil U.S. Pat. No. 4,763,929 discloses an erasable marker system that is comprised of a bracket to hold layers of a material which may be marked upon. Furthermore, the system can remove one layer of the material and replace it with another. Coster U.S. Pat. No. 4,045,013 discloses a marker board which embodies a frame, an array of annular bar rings, and a plurality of flexible shells.
The prior art has also suggested mechanisms to ease the use of boards intended to convey messages. Robins U.S. Pat. No. 4,834,334 discloses a turn and tilt easel. The easel is pivotally attached to a base to allow the base to be set on a supportive surface such as a table. Stempel U.S. Pat. No. 4,437,839 discloses a chalkboard with a hinged chalk rail. This patent discloses a indicia receiving board with a longitudinally disposed folding rail. The rail may be folded up close to the writing surface of the board. Seregely U.S. Pat. No. 3,949,132 discloses marker boards and erasable ink compositions therefore. This patent discloses the ink composition for erasable marker boards and boards having smooth, nonporous surfaces to facilitate the use of the ink.
The prior art fails to disclose an erasable marker board with the aforementioned desirable characteristics, namely lightweight, structural strength and portability. Frame corners allowing two similar frame members to be structurally and stylishly joined are extensively disclosed in the prior art. Yet, the prior art does not disclose a corner bracket that will allow a transition from a frame material with a particular cross-section to a dissimilar framing material. Such a corner bracket would be necessary to form a smooth transition between the relatively flat and compact frame to the tray portion necessarily disposed along the lower edge of a marker board. This tray is desired to hold unused marker pens or the like. Furthermore, the previously employed board assemblies fail to disclose a lightweight, portable board which can be hung upon a wall. Finally, while some of the frames disclosed by the prior art allow for a unitary frame none is suitable to provide the desired lightweight, transportable marker board.